Semiconductor circuits are increasingly being designed in which integrated circuits are stacked one above the other in a plurality of levels and are connected to one another. In particular, integrated circuits using different technologies are in this way combined.
Such stacks of different integrated circuits are combined in one chip casing, in particular in order to increase the packing density and to shorten the connecting paths. In this case, the substrates which contain the integrated circuits, may be composed of different substrate materials and/or may be manufactured using different technologies are in each case ground to a thickness of less than 10 .mu.m and are arranged as a stack. Contacts are formed in the vertical direction through the substrates. When viewed from the outside, such a component stack looks like a new semiconductor module. It can be implemented in a standard casing with a reduced number of connections, even though it has increased functionality.
Y. Hayashi et al., Symp. on VLSI Techn. (1990), pages 95 to 96, discloses a substrate being bonded by the front side, which comprises an integrated circuit, onto a stabilizing supporting plate in order to form a three-dimensional circuit. The substrate is subsequently ground to a thickness of less than 10 .mu.m from the rear side. Large-area depressions are produced in the rear side in order to make contact in a substrate which is adjacent in the stack, and these depressions are filled with a gold/indium alloy. The substrate is now stacked onto the adjacent substrate such that the rear side of the first substrate is adjacent to the front side, which comprises integrated circuits, of the second substrate. Tungsten pins are arranged in the front side of the second substrate and extend into the depressions, which are filled with the gold/indium alloy, as a result of which vertical contacts are implemented between the adjacent substrates. A polyimide layer is used as the adhesive layer in order to connect the two substrates mechanically.
The stabilizing supporting plate must subsequently be removed again in an expensive and risky process.